Fixed race condition during UCI engine startup

Lines received during engine startup sometimes needed to be processed before
the Engine object was fully initialized.

CHANGELOG.rst

@@ -18,6 +18,10 @@ Up for the next release
 * The result of the `stop` and `go` UCI commands are now named tuples (instead
   of just normal tuples).
 
+* Fixed race condition during UCI engine startup. Lines received during engine
+  startup sometimes needed to be processed before the Engine object was fully
+  initialized.
+
 New in v0.7.0
 -------------
 

chess/uci.py

@@ -549,13 +549,14 @@ def result(self, timeout=None):
 
 
 class MockProcess(object):
-    def __init__(self, engine):
-        self.engine = engine
-
+    def __init__(self):
         self._expectations = collections.deque()
         self._is_dead = threading.Event()
         self._std_streams_closed = False
 
+    def spawn(self, engine):
+        self.engine = engine
+
     def expect(self, expectation, responses=()):
         self._expectations.append((expectation, responses))
 
@@ -603,12 +604,15 @@ def __repr__(self):
 
 
 class PopenProcess(object):
-    def __init__(self, engine, command):
-        self.engine = engine
-        self.process = subprocess.Popen(command, stdout=subprocess.PIPE, stdin=subprocess.PIPE, bufsize=1, universal_newlines=True)
+    def __init__(self, command):
+        self.command = command
 
         self._receiving_thread = threading.Thread(target=self._receiving_thread_target)
         self._receiving_thread.daemon = True
+
+    def spawn(self, engine):
+        self.engine = engine
+        self.process = subprocess.Popen(self.command, stdout=subprocess.PIPE, stdin=subprocess.PIPE, bufsize=1, universal_newlines=True)
         self._receiving_thread.start()
 
     def _receiving_thread_target(self):
@@ -651,16 +655,21 @@ def __repr__(self):
 
 
 class SpurProcess(object):
-    def __init__(self, engine, shell, command):
-        self._stdout_buffer = []
+    def __init__(self, shell, command):
+        self.shell = shell
+        self.command = command
 
-        self.engine = engine
-        self.process = shell.spawn(command, store_pid=True, allow_error=True, stdout=self)
+        self._stdout_buffer = []
 
         self._result = None
 
         self._waiting_thread = threading.Thread(target=self._waiting_thread_target)
         self._waiting_thread.daemon = True
+
+    def spawn(self, engine):
+        self.engine = engine
+
+        self.process = self.shell.spawn(self.command, store_pid=True, allow_error=True, stdout=self)
         self._waiting_thread.start()
 
     def write(self, byte):
@@ -705,8 +714,8 @@ def __repr__(self):
 
 
 class Engine(object):
-    def __init__(self, process_cls, args):
-        self.process = process_cls(self, *args)
+    def __init__(self, process):
+        self.process = process
 
         self.name = None
         self.author = None
@@ -722,13 +731,15 @@ def __init__(self, process_cls, args):
         self.queue = queue.Queue()
         self.stdin_thread = threading.Thread(target=self._stdin_thread_target)
         self.stdin_thread.daemon = True
-        self.stdin_thread.start()
 
         self.return_code = None
         self.terminated = threading.Event()
 
         self.info_handlers = []
 
+        self.process.spawn(self)
+        self.stdin_thread.start()
+
     def send_line(self, line):
         LOGGER.debug("%s << %s", self.process, line)
         return self.process.send_line(line)
@@ -1257,7 +1268,8 @@ def popen_engine(command, engine_cls=Engine):
     The input and input streams will be linebuffered and able both Windows
     and Unix newlines.
     """
-    return engine_cls(PopenProcess, (command, ))
+    process = PopenProcess(command)
+    return engine_cls(process)
 
 
 def spur_spawn_engine(shell, command, engine_cls=Engine):
@@ -1271,4 +1283,5 @@ def spur_spawn_engine(shell, command, engine_cls=Engine):
 
     .. _Spur: https://pypi.python.org/pypi/spur
     """
-    return engine_cls(SpurProcess, (shell, command))
+    process = SpurProcess(shell, command)
+    return engine_cls(process)

test.py

@@ -1250,7 +1250,7 @@ def test_async_terminate(self):
 class UciEngineTestCase(unittest.TestCase):
 
     def setUp(self):
-        self.engine = chess.uci.Engine(chess.uci.MockProcess, ())
+        self.engine = chess.uci.Engine(chess.uci.MockProcess())
         self.mock = self.engine.process
 
         self.mock.expect("uci", ("uciok", ))